Took the car out yesterday for a blast on the back roads, with lots of energetic sprints between corners (among other things ). I kept the Steptronic in "Sport" mode so, although the thing was revving like a maniac at times, I never redlined or hit the limiter. Yet, I noticed when I parked up a little while later at a country pub, that there was black and green residue in one of my twin tailpipes. See the pics below ... the right pipe is what both normally look like, but you can see the black and green gunk on the left one.

This morning, the gunk was gone, but there was still some discoloration to the left pipe. Anyone got any ideas what may have caused this and what the problem could be? The residue was dry (i.e not oily), but it sure has me worried. Am on the road at the moment, so can't get into a dealer for the next couple of dayd, but desperately want to know what this is and how worried I should be.

 

Looks like your car ate some bad Indian food....



I know in the regular gasoline cars mine are blackened.h

 

MacSid,

I'm only guessing here, but I think that you have been doing some gentle running previously, which has allowed some condensation to form within one of the silencer boxes - probably the last one. With enjoying your spirited driving, the relatively high exhaust gas speeds have caused that condensation to travel as far as the tail pipe, and then the heat has taken over to evaporate it on the inner surface of the tail pipe. The green tinge suggests some form of copper compound, but with all the strange chemicals that go into modern fuels, it could be anything.

Odd isn't it, that no matter how hard you try on a 530d, you can never get the same colour on each tail pipe! Mine is exactly the same - diesel black on one side and shiny new on the other. I suppose that's the "penalty" of not having the valve fitted to the rear silencer on the 530d like it is on the other models.

None of the BMW "Techs" (and I use the word loosely, as I haven't yet spoken to one who seems knowledegable about the E60) I have spoken to have even noticed the odd coloured pipes, never mind know why one pipe doesn't seem to be "used".

Mike

 

Mike,

You're absolutely spot on with your assumption on gentle running. My normal day to day use of the car rarely sees speeds of over 60mph and there is certainly zero room on my commute to get it revving excitedly (i.e. over 2,500rpm) either. Your explanation seems to cover it, and I certianly hope it's nothing more sinister than that.

My tailpipes have both been shiny new from the time I got the car in March this year right up to last weekend, so you can imagine why I got worried - and this is not the first time the car has been run hard.

 

The diesels have particulate filters which periodically get burnt off (I think). It may be that your engine computer decided that the long high-rev run would be a good time to do a burn. In which case, the green/yellow stuff could possibly be sulphur (sulfer for the yanks that's been spat out the particulate filter. Given the physical properties of sulphur, it could actually boil off, and then condense/solidify on the tail pipe.

But all that is pure guesswork, to be honest . There is a reasonable amount of sulphur in most diesel fuel, although to be honest I'd expect it to burn and come out your exhaust as sulphuric oxides rather than get particles of the stuff trapped in the filter.

Andrew

 

read through throughly, should i be worried, or is this a common thing, as i noticed this quite some time ago, like when i was on the motorway runs, saying that i kept ahead of a EVO 9 yesterday at around 135ish, and then had to slow for cars, but i had a 5-6 car lenghths on him, but they were slowly becoming 2 car lenghths, fun never the less!!!!

 

Maybe something crawled up there in the night ????